Fin peening tool



April 4, 1950 F. s. SHERWIN FIN PEENING TOOL Filed Dec. 7, 1946 INVENTOR F REDERI K 5. S HERWIN ATTORNEY Patented Apr. 4, 1950 FIN PEENING TOOL Frederick S. Sherwin, Fairlawn, N. J., assignor to Wright Aeronautical Corporation, a corporation of New York ApplicationDecember 7, 1946, Serial No. 714,891

1 Claim. 1

This invention relates to peening tools and is particularly directed to a peening tool which is formed so as to control the flow of the peened metal.

The tool of the present invention has been designed for use with the fin brace members disclosed in Patent No. 2,398,216. This prior patent discloses a fin brace member which is held in position on the cooling fins of an engine cylinder by peening the outer edges of the fins. When a conventional peening tool, similar to a cold chisel, is used to peen over the fins, only a relatively small amount of the fin metal of each fin is displaced with the result that the fin brace members are insecurely held in position. Thus, the peened or displaced fin metal is relatively jagged or sharp cornered so that this metal tends to crack.

An object of the present invention comprises the provision of a peening tool which is adapted to peen over the edges of the fins along substantially the entire length of the portions of the fins projecting through their associated fin brace members. In addition, the peening tool of the present invention is designed to control the flow of the displaced metal so as to provide a wellrounded peen which securely holds the fin brace member in position on the fins. Other objects of the invention will become apparent upon reading the annexed detailed description in connection with the drawing in which:

Figure 1 is a view in elevation of a group of fins and associated fin brace members after the fins have been peened with a conventional cold chisel type of peening tool;

Figure 2 is a sectional view taken along line 2--2 of Figure 1 and illustrating a conventional prior art peening tool in position over the fins;

Figure 3 is a side view of a peening tool embodying the present invention;

Figure 4 is an enlarged view of a portion of the operating end of the tool illustrated in Figure 3;

Figure 5 is a sectional view taken along line 5-5 of Figure 4;

Figure 6 is a view in elevation of a group of fins and associated fin brace members after the fins have been peened over with the tool of the present invention;

Figure '7 is a view taken along line of Figure 6 and illustrating the peening tool of the present invention in position over a group of fins and the associated fin brace member;

Figure 8 is a sectional view taken along line 8-8 of Figure 7; and

Figure 9 is a view similar to Figure '7 but of a modified form of peening tool.

Referring first to the prior art, as illustrated into that disclosed in Patent No. 2,398,216 extendsacross the fins I2 with the fins projecting through slots M in the fin brace member ID. As illustrated, each of the fins l2 has been peened over at It with a blunt edged peening tool l8 similar to a cold chisel. This results in a sharp cornered peen .with only a relatively small amount of the fin metal projecting through the brace member ID actually being peened over. Accordingly, with this prior art practice, the displaced fin metal tends to crack so that the brace member I 0 is not provided with a durable lock for holding it in position on the fins l2.

Referring now to Figures 3 to 8, the peening tool 20 of the present invention comprises a body portion having a plurality of parallel ribs 22 projecting from a ridge extending across one end of said tool. The parallel ribs 22 are provided with a spacing equal to the spacing of the fins l2 to be peened over and are adapted to extend therebetween in the clearance relation with the fins. In this way, the parallel ribs 22 form parallel grooves 24 which are made somewhat wider than the fins to be peened thereby. The bottom surface of each groove 24 is convex longitudinally of the groove and concave transversely on the groove. Thus, as illustrated, the convex curvature longitudinally along the bottom of each groove is a circular are having a radius as indicated at 26 (Figure 5) while the concave curvature across the bottom of each groove is a circular are having a radius as indicated at 28 (Fig- 4).

svhen the fins are to be peened, the tool 20 is placed in position with the ribs 22 pro ecting between the fins and the outer end of the tool is struck by a hammer-like instrument. As a result, during the peening operation, the metal at the outer edge of each fin flows transversely to substantially fill the arcuate space in the bottom of its associated groove. That is, the round bottom surface of each groove is effective to form a well-rounded bulbous shape 30 along substantially the entire length of that portion of the outer edge of each fin projecting through the associated fin brace member. This results in a relatively long lasting structure for rigidly securing the associated fin brace member I 0 to the fins 12. Also, the concave curvature at the bottom of each groove 24 is effective to center the tool 20 in position over the fins during the peening operation.

The magnitude of the peening operation is limited by the shoulders 32 projecting from the sides of the tool and adapted to engage the material of the fin brace member IB extending across the outer surface of the fins l2.

In the fin structure illustrated in the aforementioned patent, the surface defined by the outer edge of each group of fins is normal to the plane of each fin of the group. However, each fin of a group may project outwardly "to a difierent extent from its adjacent fin. For example, the outer edges of the fins 34 (Figure 9) define a surface inclined to the plane of each fin 34. Accordingly, a peening tool 36 is modified, as illustrated, from the peening tool 20 so that the bottoms of the parallel grooves '38 in the tool define a line or plane inclined to the tool axis similar to the inclination of the surface defined by the outer edges of the fins 34 to the plane .of each of these fins. In this way, the tool .36 may be used for simultaneously peening the ends of the fins 34. Thus, a tool 36 similar to the tool 20 maybe used to peen 'a plurality of fins provided the bottom of the peeninggrooves 38 of the tool 3'6-occupy -the same relative position as the ends of the fins 34 to be peened thereby.

The peening tool of the present invention has been illustrated and described for peening over the edges of the'cooling fins projecting from an engine cylinder. However, the tool obviously is not limited to this .specificuse and may be used for peening other-than fins.

While I have described my invention in detail in its present preferred embodiment, it will be obvious to those skilled in the art, after understanding my invention, that various changesand modifications may be made therein without departing from the spirit or scope thereof. I aim in the appended claim to cover all such modifications.

I claim as my invention:

A peening tool comprising a body portion having one end adapted to be struck by a hammer-like instrument and having an elongate ridge across and projecting from the other end of said tool, said ridge having a plurality of paced parallel grooves extending thereacross thereby providing alternate ribs and grooves extending across said ridge with the transverse width of each groove being less than its longitudinal length, said ribs being arranged to project between, and in clearance relation with, the material to be peened whereby thesurfaces of said grooves control the fiow of the peened material, the bottom of each of said grooves having a convex curvature longitudinally thereof and having a concave curvature transversely of the groove, said concave curvature being substantially greater than said convex curvature.

FREDERICK S. SHERWIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 63,474: Connolly Apr. 2, 1867 491,997 Faulds Feb. 21, 1893 1,650,055 Tregillus Nov. .22, 1927 FOREIGN PATENTS Number Country Date 105,821 Germany Nov. 23, 1899 

